Bearded and still burly after triple bypass surgery, 60-year old Martin Sanderson walks with a bit of a stoop. His demeanor conveys authority. Government workers in agencies he formerly administered probably got busy when he walked into the room. People still listen when he speaks, from a microphone now, on a stage, delivering spoken word poems, increasingly on the subject of climate change.

In 1761 Francis Egerton, the 3rd Duke of Bridgewater, built England’s first modern canal, revolutionising transport, and triggering an investment boom that transformed the nation. Two and a half centuries later his innovation reverberates in the form of 2000 miles of canals and towpaths...